Defrosting glass plate and method for manufacturing same



NOV. 26, 1940. A. M. DUCRET Erm. 2,222,742

DEFROSTING GLASS PLATE AND METHOD FOR MANUFACTURING SAME Filed July 6, 1958 2 Sheets-Sheet l TEA- E- i l-1 4- Fig E Nov. 25, 1940. A, M DUCRET Em 2,222,742

DEFROSTING GLASS PLATE AND METHOD FOR MANUFACTURING SAME Filed July e, 195e 2 Smets-sheet 2 Fig f5? Ji jg J0 .X1 Xy o ,y `J7 Patented Nov. 26, 1940 unirse ys'ra'rss Paras? ortica ecrans Application July 8, 1938, Serial No. Bll In France July 15, 193'? Defrosting glass plates have already been mam ufactured by arranging a series of heating wires, which are often of fairly large cross-section, between two glass plates which are spaced some 's distance apart: a rising current of hot airis thus created which, by convection, heats the visibility glass plat-e'which is lia-ble to frost. But the devices ot this kind have various drawbacks: on the one hand, the heating is imperfect and lacks m uniformity; on the other hand, it is found that the hot air which is set in motion deposits its dust on the glass no doubt owing to electrification phenomena.

The present invention consists in arranging fine electric resistance wires in intimate and close contact with the glass plate over their entire usefui length, in such a manner that the lglass plate is directly heated vby conductivity.

Said fine wires, which are as numerous as nec essary according to the magnitude of the rise of temperature to be eiiected, are spaced from i to 3 cm. apart according to cases and, vowing to 'their small diameter, they do not in practice affect visibility.

They are preferably fixed at their ends by means of metallized strips which at the same time ensure the supply of the current.

u Owing to its thermic conductivity, the glass itself ensures the uniform distribution oi heat that is necessary for obtaining a uniform defrosting.

dium silicate, organic glass, cellulose, ete); or'

with two thicknesses of glass, and in this case said conductors will advantageously be enveloped in an interstitial layer made of a, solid, transparent substance which is a good conductor o! heat (such as sodium silicate, organic glass, etc.) its being possible ior said substance to serve at the same time for cementing the glass plates on each other.

The resistance wires may also be embedded in the thickness of the glass, either by forming suitable hollow grooves in the latter, or by sinking the wire into the glass in the hot state before said glass has hardened.

The invention furthermore includes a method for manufacturing glass plates of this kind which comprises stretching thev wires beforehand on a frame, giving then the suitable pattern, placing It is possible either to construct such a de-` (Ci, Zig- 19? the frame thus equipped on the pane, and nzlug the useful parts on the glass plate, in particular by aihxing a metallized layer, then cutting 'the ends of the Wires and removing the frame.

By way of example and in order to enhance the comprehension of the present description, there have been shown in the accompanying drawings in:

Figures 1, 2, 3 and 4, sectional views of deirostlng glass plates according to the present invention.

Figures 5 and 5, respectively plan and side elevational views of a frame for placing the stretched wires in position.

Figures 7 and 8, diagrammatical views of excmplary embodiments of defrostlng glass plates according to the present invention.

Figure 9 the diagrammatical view ci a removable defrosting glass plate.

in the exemplary embodiment shown in Figure l, the wires are placed on the surface of a pane or the like i madeoi glass or of any other appropriate transparent material and are fixed by a transparent and adherent coating 3.

In the example shown in Figure 2, they are on the contrary arranged between two panes 4 and 5 and the interstitial space is filled with a transparent and adherent material i.

In the example shown in Figure 3, the wires are lodged in grooves l provided in the pane 8. Said grooves may ln particularhave 'been impressed in the' glass during the manufacture of .the pane, before it has completely cooled, or again, the wires themselves may have been driven by pressure into the vitrified mass before it has completely cooled. Y

In this latter example. the wires may be replaced by metal braid or strips oi small thickness but of substantial width, placed edgewise. The example shown in Figure 4 illustrated the case of metal strips 22 embedded in the thickness of two juxtaposed panes. l

In these various examples, the wires will preierably have a diameter of oo to 2%00 0f a millimetre: the braid or strips will have a similar thickness and a Width o1 the order of 1 to 4 millimetres.

The fixing of the ends o! the wires and the supply of same with current will be effected, according to the invention, by means of metallized strips obtained for example by projection of molten metal, such as the strips shown at 9 and l0 in Figure 7. Said strips may either be simply deposited on the actual surface of the pane, or

`manuiacture of electric resistances,

be deposited in a groove formed in the thickness oi' the glass.

Instead of being obtained by projection o! molten metal, said strips may be formed by fiat pieces oi metal on which the resistance wires are welded or fixed by any appropriate means.

It is rather dimcult to obtain an emcient distribution of the resistance wires over the surface of the glass plates. For this purpose, according to the present invention, the following method may be employed:

The resistance wires r1, fr. n. etc. are stretched on the studs t1, tz, t: etc. carried by the crosspieces Il and I2 oi a frame Il (Figures 5 and 6) the cross-piece ills fixed and the cross-piece l2, which can move in the guiding slide-ways 2l and 24 oi the side members of the i'rame, is constantly drawn in the direction of the arrow f by the tension springs RiB/l. While the wires are beina placed in position said crosspiece is locked by the removable stops C1 and Cs.

When all the wires nur: etc. are mounted on the studs titzt: etc. the stops C1 and C: are removed and the wires remain stretched.

, The frame is then placed on the pane andl the xing oi the wires is eflected, for example by depositing by means of a metallizing pistol. the fixing and current supply strips represented by the hatched strips I3 of Figure 5. 'Ihe ends of the wires are then cut and the frame may be removed.

The wires being thus fixed on the pane by their ends. the deposit is then effected of the protecting and ilxing layer shown at I (Figures 1 and 3) or at i (Figure 2) and, if necessary, the second pane is aillxed ii the glass plate is formed by a double pane according to the example ci Figure 2. Nothing then remains to be done but to complete the device by .mounting plusI sockets il, switchesl I5 etc. (Figures 7. 8 and 9) at the starting point of the metallized strips.

For the wires metal braid or strips, any metals will be employed that are usually used for the suchas nickel. chromium, constantan, etc.

For the metalllzed or metal strips supplying the current, a good conducting metal will preferably be used, the coeiiicient of expansion of which is nearly that of glass.

'Ir'he glass may be replaced by any transparent substance which is appropriate for manufacturlng glass panes or plates.

The coatings or transparent interstitial layer: may in particular be formed by sodium silicate, organic glass or any transparent organic materials which are capable ot withstanding the temperature contemplated. 'nie thermic conductivity oi' such materials is in general higher than that oi glass, thereby offering an additional 'advantage for the emcient distribution of the heat.

The arrangement of the wires or strips may be very variable according to' the purposes contemplated.

In the example shown in Figure 'I thesuri'ace of the glass plate is divided into two parts which' can be supplied separately. The-right hand part is supplied by the metallised strip Il and the left hand part by the metalliaed strip Il'. Any appropriate switch I5 enables either of said parte to be heated, or both simultaneously.

In the example shown in Figure 8, the current from the yplug I8 is distributed in the sheet of resistance wires by the metallized strips I1. Said wires are arranged in' polygonal formations and the particular formations shown in this example enables a more intense heating to be obtained at the centre of the surface: very fine equipotential metallizations :in -mi-me-nn, which are arranged along the points oi change oi' direction oi' the wires, ensure the nxing of the wires to the glass.

Another embodiment, which is the obiect of Figure 9. consists in constructing the previously described heating unit on a glass plate of more reduced dimensions than those oi the glass plate to be defrosted and in applying said heating unit externally or internally on the part to` be heated. 'I'his removable device in this case comprises a frame 20 carrying xing meanssuch as suckers il and the plug socket Il together with a switch I8. A rubber bead Il ensures a certain amount of fluid-tightness for the space between the heatsame conditions to non-transparent surfaces, in

particular made of porcelain.'-

It covers, by way of new industrial products, the glass plates or elements of glass plates thus constructed and also the removable devices thus constructed which are intended to be iixed on the panes to be defrosted.

Having now particularly described and ascertained the nature of our said invention and in what manner vthe same is to be performed, we declare that what m claim is:

1. A defrosting plate comprising at least one transparent plate, a plurality of electrical conductor wires in tensioned state thereon, means lor aliking said wires to said plate and for retaining them in said tensioned state, said means comprising a plurality of spaced adherent strips oi' metal deposited over an area oi substantial width on one face of said plate and extending over said'wires transversely of the latter, a layer of electrical non-conducting material covering the said wires and the said strips, and lcurrent supply means electrically connected to the said strips.

2. A detrosting plate comprising at least one transparent plate, a plurality oi electrical conductor wires in tensioned state thereon, means for aiiixing said wires to said plate and for retaining them in said tensioned state, said means comprising a plurality of spaced adherent strips of metal deposited over an area of substantial width on one face of said plate and extending over said wires transversely of the latter, a layer oi.' electrical non-conducting material covering the said wires and the said strips, and current supply means electrically connected to the said strips, the said layer of electrical non-conducting material consisting of a second transparent plate.

3. A defrosting plate comprising at least one transparent plate. a plurality o! electrical conductor wires in tensioned state thereon, means for amxing said wires to said plate and for retaining them in said tensioned state, said means comprising a plurality of spaced adherent strips of metal deposited over an area o! substantial width lon one face of said plate and extending over said wires transversely of the latter. a layer of electrical non-conducting material covering the said wires and the said strips, and current supply means electrically connected to the said strips, the said strips being substantially spaced from the edges of the said plate.

4. A method for the manufacture of a defrosting plate including a supporting transparent plate, electric heating wires, and a metallic connection between said plate and wires, said method comprising arranging an electric heating Wire to provide a plurality of substantially coextensive spaced parallel runs and connecting loops inter mediate the several runs, tensioning said several runs by applying tensioning forces at said loops, maintaining said wire in the resultant tensioned state, applying said wire in the said state to a surface of said supporting plate, aiilxing said runs ln tensioned state to said plate by depositing adherent metallic strips over said plate and runs transversely of and. intermediate the ends o the latter, and at substantial distances from each other and from the edges of said plate, said strips being of substantial width, extending said metallic strips so that the ends thereof terminate adjacent an edge of said plate and in proximity to each other, whereby said ends may be readily associated with a source of current supply, then cutting the portions of said runs extending on the said strips, applying an insulating layer over the said runs and strips, and nally connecting the said strips with a current supply means,

' ANDR MAXIME DUCRET.

JEAN ROBERT RIDEAU. 

